Oxidation of ammonium perchlorate (AP) was used to remove organic templates of ordered mesoporous materials at relatively low temperature (100 ℃). SBA-15 prepared by using triblock copolymers P123 as a template was chosen as an example to demonstrate the AP-HNO₃ treatment method. The resultant template-free product (N-SBA-15) had a larger pore size (10.4 nm) and volume (1.40 cm³·g^-1) compared to the calcined sample (6.5 nm and 1.03 cm³·g^-1). The IR spectrums show that N-SBA-15 has a high concentration of surface silanol groups. No framework shrinkage is observed based on XRD results. TEM images show that N-SBA-15 has a highly ordered two-dimensional hexagonal structure (p6mm). Moreover, N-SBA-15 shows almost no micropore volumes. Therefore, high quality N-SBA-15 can easily be obtained under mild conditions. This strategy can also be extended to prepare other template-free mesoporous silicas, such as those with space groups of Fm3m, Im3m, and Ia3d.